表格与脚注

                    if mode == TableParseMode::Scan && pipes > 0 {
                        // check if we may be parsing a table
                        let next_line_ix = ix + eol_bytes;
                        let mut line_start = LineStart::new(&bytes[next_line_ix..]);
                        if scan_containers(&self.tree, &mut line_start, self.options, false)
                            == self.tree.spine_len()
                        {
                            let table_head_ix = next_line_ix + line_start.bytes_scanned();
                            let (table_head_bytes, alignment) =
                                scan_table_head(&bytes[table_head_ix..]);

                            if table_head_bytes > 0 {
                                // computing header count from number of pipes
                                let header_count =
                                    count_header_cols(bytes, pipes, start, last_pipe_ix);

                                // make sure they match the number of columns we find in separator line
                                if alignment.len() == header_count {
                                    let alignment_ix = self.allocs.allocate_alignment(alignment);
                                    let end_ix = table_head_ix + table_head_bytes;
                                    return LoopInstruction::BreakAtWith(
                                        end_ix,
                                        Some(Item {
                                            start: i,
                                            end: end_ix, // must update later
                                            body: ItemBody::Table(alignment_ix),
                                        }),
                                    );
                                }
                            }
                        }
                    }

| a | b |         ->  段落，两行文字        没有分隔行
| c | d |

| a | b |         ->  段落，两行文字        2 列对 1 列
| --- |

Hello / | a | b | / |---|---|  ->  <p>Hello</p><table>…
Hello / a | b / --|--          ->  <p>Hello\na | b\n--|--</p>

355..439 Start(Table([Left, Right]))
  355..372 Start(TableHead)
    356..361 Start(TableCell)
      357..360 Text(Borrowed("遍"))
    356..361 End(TableCell)
    ...
  355..372 End(TableHead)
  386..415 Start(TableRow)
    387..398 Start(TableCell)
      388..397 Text(Borrowed("第一遍"))
    387..398 End(TableCell)
    399..413 Start(TableCell)
      400..412 Code(Borrowed("Tree<Item>"))
    399..413 End(TableCell)
  386..415 End(TableRow)
  ...
355..439 End(Table)

                        } else if bytes[ix + 1] == b'|' && TableParseMode::Active == mode {
                            // Yeah, it's super weird that backslash escaped pipes in tables aren't "real"
                            // backslash escapes.
                            //
                            // This tree structure is intended for the benefit of inline analysis, and it
                            // is supposed to operate as-if backslash escaped pipes were stripped out in a
                            // separate pass.
                            begin_text = ix + 1;
                            backslash_escaped = false;
                            LoopInstruction::ContinueAndSkip(1)

| 写法 | 结果 |
|:-|--:|
| `a\|b` | r \| s |
| \\| y |

  29..49 Start(TableRow)
    30..38 Start(TableCell)
      31..37 Code(Boxed("a|b"))
    30..38 End(TableCell)
    39..47 Start(TableCell)
      40..42 Text(Borrowed("r "))
      43..46 Text(Borrowed("| s"))
    39..47 End(TableCell)
  29..49 End(TableRow)
  49..59 Start(TableRow)
    50..57 Start(TableCell)
      53..56 Text(Borrowed("| y"))
    50..57 End(TableCell)
    59..59 Start(TableCell)
    59..59 End(TableCell)
  49..59 End(TableRow)
0..59 End(Table)

  5721..5728 Start(TableRow)
  ...
  5721..5728 End(TableRow)
  5728..5728 Start(TableRow)
  ...
  5728..5728 End(TableRow)
  5728..6000 Start(Paragraph)
    5728..5734 Text(Borrowed("|x262|"))
    5734..5735 SoftBreak
    5735..5741 Text(Borrowed("|x263|"))
  ...
  5728..6000 End(Paragraph)
0..6000 End(Table)

        const ENABLE_FOOTNOTES = 1 << 2;
        // ...
        const ENABLE_OLD_FOOTNOTES = (1 << 9) | (1 << 2);

    fn parse_footnote(&mut self, start: usize) -> Option<usize> {
        let bytes = &self.text.as_bytes()[start..];
        if !bytes.starts_with(b"[^") {
            return None;
        }
        let (mut i, label) = if self.options.has_gfm_footnotes() {
            // GitHub doesn't allow footnote definition labels to contain line breaks.
            // It actually does allow this for link definitions under certain circumstances,
            // but for this it's simpler to avoid it.
            scan_link_label_rest(&self.text[start + 2..], &|_| None, self.tree.is_in_table())?
        } else {
            self.parse_refdef_label(start + 2)?
        };
        // ...
        i += 2;
        if bytes.get(i) != Some(&b':') {
            return None;
        }
        i += 1;
        self.finish_list(start);
        if let Some(node_ix) = self.tree.peek_up() {
            if let ItemBody::FootnoteDefinition(..) = self.tree[node_ix].item.body {
                // finish previous footnote if it's still open
                self.pop(start);
            }
        }
        if self.options.has_gfm_footnotes() {
            i += scan_whitespace_no_nl(&bytes[i..]);
        }
        self.allocs
            .footdefs
            .0
            .insert(UniCase::new(label.clone()), FootnoteDef { use_count: 0 });
        // ...
    }

[^1]: 一
[^2]: 二

[^3]:

    第一段

    第二段

引用 [^1] [^3] [^4]

...
21..58 Start(FootnoteDefinition(Borrowed("3")))
  32..42 Start(Paragraph)
    32..41 Text(Borrowed("第一段"))
  32..42 End(Paragraph)
  47..57 Start(Paragraph)
    47..56 Text(Borrowed("第二段"))
  47..57 End(Paragraph)
21..58 End(FootnoteDefinition)
58..80 Start(Paragraph)
  58..65 Text(Borrowed("引用 "))
  65..69 FootnoteReference(Borrowed("1"))
  69..70 Text(Borrowed(" "))
  70..74 FootnoteReference(Borrowed("3"))
  74..75 Text(Borrowed(" "))
  75..76 Text(Borrowed("["))
  76..78 Text(Borrowed("^4"))
  78..79 Text(Borrowed("]"))
58..80 End(Paragraph)

...
21..28 Start(FootnoteDefinition(Borrowed("3")))
21..28 End(FootnoteDefinition)
32..57 Start(CodeBlock(Indented))
  32..43 Text(Borrowed("第一段\n\n"))
  47..57 Text(Borrowed("第二段\n"))
32..57 End(CodeBlock)
58..80 Start(Paragraph)
  58..65 Text(Borrowed("引用 "))
  65..69 FootnoteReference(Borrowed("1"))
  69..70 Text(Borrowed(" "))
  70..74 FootnoteReference(Borrowed("3"))
  74..75 Text(Borrowed(" "))
  75..79 FootnoteReference(Borrowed("4"))
58..80 End(Paragraph)

[^1]: a
- 列表

正文

        // parse refdef
        while let Some((bytecount, label, link_def)) =
            self.parse_refdef_total(start_ix + line_start.bytes_scanned())
        {
            self.allocs.refdefs.0.entry(label).or_insert(link_def);
            let container_start = start_ix + line_start.bytes_scanned();
            let mut ix = container_start + bytecount;
            // ...
            if let Some(nl) = scan_blank_line(&bytes[ix..]) {
                ix += nl;
            } else {
                self.finish_list(start_ix);
                return ix;
            }
            if let Some(lazy_line_start) = self.scan_next_line_or_lazy_continuation(&bytes[ix..]) {
                line_start = lazy_line_start;
                start_ix = ix;
            } else {
                self.finish_list(start_ix);
                return ix;
            }
        }

[Foo] [ẞ] [a   b] [q]

[foo]: /first
[FOO]: /second
[SS]: /eszett
[A b]: /ws
段落
[x]: /not-a-def

> [q]: /in-quote

refdef "A b" -> Borrowed("/ws") title=None span=68..78
refdef "SS" -> Borrowed("/eszett") title=None span=54..67
refdef "foo" -> Borrowed("/first") title=None span=25..38
refdef "q" -> Borrowed("/in-quote") title=None span=105..119
0..24 Start(Paragraph)
  0..5 Start(Link { link_type: Shortcut, dest_url: Borrowed("/first"), title: Borrowed(""), id: Borrowed("Foo") })
  0..5 End(Link)
  6..11 Start(Link { link_type: Shortcut, dest_url: Borrowed("/eszett"), title: Borrowed(""), id: Borrowed("ẞ") })
  6..11 End(Link)
  12..19 Start(Link { link_type: Shortcut, dest_url: Borrowed("/ws"), ...
  12..19 End(Link)
  20..23 Start(Link { link_type: Shortcut, dest_url: Borrowed("/in-quote"), title: Borrowed(""), id: Borrowed("q") })
  20..23 End(Link)
0..24 End(Paragraph)
79..102 Start(Paragraph)
  85..86 SoftBreak
79..102 End(Paragraph)
103..120 Start(BlockQuote(None))
103..120 End(BlockQuote(None))

  59..73 Start(TableRow)
    60..63 Start(TableCell)
      61..62 Text(Borrowed("`"))
      62..63 Text(Borrowed("p"))
    60..63 End(TableCell)
    64..67 Start(TableCell)
      64..65 Text(Borrowed("q"))
      65..66 Text(Borrowed("`"))
    64..67 End(TableCell)
  59..73 End(TableRow)
0..73 End(Table)